The present invention relates to perylene derivatives of the general formula I 
where
X and Y are independently oxygen, xe2x80x94NR1 or xe2x80x94NR2;
R1 and R2 are independently hydrogen, C1-C18-alkyl, C5-C7-cycloalkyl, aryl or C1-C6-alkoxy;
R3 to R10 are independently hydrogen, hydroxyl or aryl, although radicals conjointly attached to one carbon atom may also be xe2x95x90O or xe2x95x90CHR11,
R11 is hydrogen or C1-C3-alkyl,
with the proviso that said perylene derivative I contains from at least one to not more than three carbonyl groups per molecule.
This invention also relates to the use of perylene derivatives I as crystallization modifiers for organic pigments and also to pigment preparations comprising the perylene derivatives I.
Perylene pigments are well known. They are notable for their high color strength and light- and weatherfastnesses and are of major importance for paint and plastics coloration. As examples of particularly interesting representatives of this class of pigment there may be mentioned N,Nxe2x80x2-dimethylperylene-3,4,9,10-tetracarboxylic diimide (C.I. Pigment Red 179), N,Nxe2x80x2-bis(4-phenylazophenyl)perylene-3,4,9,10-tetracarboxylic diimide (C.I. Pigment Red 178 and N,Nxe2x80x2-bis(3,5-dimethylphenyl)-perylene-3,4,9,10-tetracarboxylic diimide (C.I. Pigment Red 149).
However, the synthesis of these pigments gives rise to crude pigments having a technically unfavorable particle shape and size, which are in need of an aftertreatment, for example as described in DE-A-21 53 087, or a salt grinding or kneading operation in order that they may be converted into a useful pigmentary form.
It is also known to add substances to influence the crystallization of the crude pigment and promote the formation of transparent pigments. For instance, in EP-A-807 668 the crude pigment is for this purpose subjected to an acid swell in the presence of anthanthrone, quinacridone and flavanthrone pigments. WO-A-91/02034 describes dispersants which are based on perylene-3,4,9,10-tetracarboxylic monoanhydride monoimides or diimides substituted by alkylene- or arylene-sulfonic acid groups on either or both imide nitrogen atoms, and which coat the pigment surface. However, these pigment preparations have different color properties as a result of the added pigment, or have only limited utility.
It is an object of the present invention to provide crystallization modifiers that will provide transparent perylene pigments having excellent application and color properties.
We have found that this object is achieved by the perylene derivatives of the formula I defined at the outset and by their use as crystallization modifiers for organic pigments.
The present invention further provides pigment preparations comprising
A) at least one organic pigment from the class of the perylene pigments and
B) at least one perylene derivative of the formula I and optionally
C) at least one rosin.
Any alkyl appearing in the formula I may be straight-chain or branched. It contains up to 18 carbon atoms, although C1-C4-alkyl radicals, especially methyl, are preferred. Specific examples are: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, 2-methylpentyl, heptyl, 1-ethylpentyl, octyl, 2-ethylhexyl, isooctyl, nonyl, isononyl, decyl, isodecyl, undecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl (the above designations isooctyl, isononyl, isodecyl and isotridecyl are trivial names derived from the alcohols obtained by the oxo process).
Useful cycloalkyl radicals are cyclopentyl, cyclohexyl and cycloheptyl.
Examples of useful aryl radicals include as well as xcex1- and xcex2-naphthyl especially phenyl and substituted phenyl such as 4-phenylazophenyl and alkyl-substituted phenyl, eg. 3,5-dimethylphenyl, which alongside C1-C4-alkyl are preferred meanings of R1 and R2.
Any alkoxy appearing in the formula I may likewise be straight-chain or branched. Examples are methoxy, ethoxy, isobutoxy, sec-butoxy, tert-butoxy, pentoxy, isopentoxy, neopentoxy, tert-pentoxy and hexoxy.
Preference is given to perylene derivatives of the formula I where the R5 and R6 pair and the R7 and R8 pair are each xe2x95x90O, i.e. perylene derivatives that contain at least two carbonyl groups.
Particular preference is given to perylene derivatives of the formula I where R3, R4, R9 and R10 are each hydrogen or hydroxyl, although the R3 and R4 pair or the R9 and R10 pair can also be xe2x95x90O, and the R5 and R6 and the R7 and R8 pairs are each xe2x95x90O.
Preferably in this context only one in each pair of radicals bonded to one carbon atom is hydroxyl.
Examples of very particularly preferred perylene derivatives are:
Particular emphasis is in this connection given to the perylene derivatives Ia, Ib, Ie and Ik.
The perylene derivatives I according to the invention may be prepared starting from perylene-3,4,9,10-tetracarboxylic anhydride, N-substituted or unsubstituted perylene-3,4,9,10-tetracarboxylic monoanhydride monoimides or N,Nxe2x80x2-substituted or unsubstituted perylene-3,4,9,10-tetracarboxylic diimides as reactants.
Reduction of these reactants is an advantageous way to obtain the particularly preferred perylene derivatives of the formula I where R3, R4, R9 and R10 are each hydrogen or hydroxyl, although the R3 and R4 pair or the R9 and R10 pair can also be xe2x95x90O, and the R5 and R6 and the R7 and R8 pairs are each xe2x95x90O.
The reducing agents used for this reduction are preferably complex hydrides of the general formula II
M1(M2HmRxe2x80x2n)pxe2x80x83xe2x80x83II
where
M1 is a p-valent metal cation such as lithium, sodium, magnesium or aluminum;
M2 is boron or aluminum subject to the proviso that M1xe2x89xa0M2;
Rxe2x80x2 is alkyl or alkoxy or, when M2 is boron, cycloalkyl containing the boron atom in the ring;
m is from 1 to 4;
n is from 0 to 3 subject to the proviso that m+n 4;
p is from 1 to 3.
Examples of useful hydrides II are LiBH4, NaBH4, LiAlH4, NaAlH4, Mg(BH4)2, Al(BH4)3, LiAlH[OC(CH3)3]3, NaAlH2(C2H5)2 and NaAlH2(OC2H4OCH3)2. Of these, sodium borohydride and lithium aluminum hydride are preferred.
The reaction with the hydride II can be carried out in aqueous phase or in an organic solvent.
When sodium borohydride is used, a particularly useful reaction medium is water or a dipolar aprotic solvent that does not react with the hydride, eg. dimethyl sulfoxide, N-methylpyrrolidone or dimethylacetamide.
When lithium aluminum hydride is used, it is preferable to use an apolar aprotic solvent, for example tetrahydrofuran or diethyl ether.
Specific selection of the reaction conditions (amount of hydride II, reaction temperature and reaction time) provides trouble-free control over the reduction.
This will now be illustrated using the perylene derivatives Ia to Ic according to the invention as an example. They are advantageously preparable from perylene-3,4,9,10-tetracarboxylic dianhydride as follows:
Since in the case of these perylene derivatives I only one side of the molecule is to be reduced, it is advisable first to convert the perylene-3,4,9,10-tetracarboxylic dianhydride into the monopotassium salt, which additionally possesses higher solubility. This, after intermediate isolation or directly, can be reacted with the hydride II (eg. sodium borohydride, amount based on 1 g of perylene-3,4,9,10-tetracarboxylic dianhydride) under the conditions set out hereinafter:
0.9-1.1 g of hydride II, 10-15xc2x0 C., 45-55 hxe2x86x92perylene derivative Ib;
1.8-2.2 g of hydride II, 50-80xc2x0 C., 2-4 hxe2x86x92perylene derivative Ia;
3.5-4.0 g of hydride II, 90-95xc2x0 C., 4-7 hxe2x86x92perylene derivative Ic.
After the reaction has ended, the potassium salt is converted back into the anhydride form with an acid.
It will be appreciated that the perylene-3,4,9,10-tetracarboxylic dianhydride can also be hydrogenated directly. However, owing to the lower solubility of the anhydride, higher reaction temperatures, longer reaction times and larger amounts of hydride II are needed, which is why the perylene derivatives I can frequently not be specifically prepared in this way, mixtures of various reaction products being obtained instead.
Reaction with the desired, preferably primary, amine (alkyl-, cycloalkyl-, arylamine) can then be used to convert the perylene derivatives Ib and Ic of the invention into the corresponding imides Id and If. In the case of Ia, this route customarily produces the imide Ie in a mixture with the unreduced pigment. The reaction medium used can be water or an alcohol, for example ethanol, or mixtures thereof, although water is preferred. The reaction temperatures generally range from 60 to 90xc2x0 C., and the reaction can be carried out under atmospheric or superatmospheric pressure.
As further examples of inventive perylene derivatives of formula I where X is xe2x80x94NR1 and Y is oxygen there may be mentioned the perylene derivatives Ig and Ih, which may be prepared analogously from the N-alkyl-substituted perylene-3,4,9,10-tetracarboxylic monoanhydride monoimide via the potassium salt using from 0.7 to 1 g of sodium borohydride per g of monoanhydride monoimide at from 55 to 60xc2x0 C. over 40-55 h.
Furthermore, inventive perylene derivatives of the formula I where X and Y are each xe2x80x94NR1 are obtainable by reacting the corresponding N,Nxe2x80x2-disubstituted perylene-3,4,9,10-tetracarboxylic diimide with the hydride II by grinding at the same time. Since this reaction requires temperatures of about 100-120xc2x0 C., it is advantageous to use a high boiling organic solvent, for example dimethyl sulfoxide, as reaction medium. The reaction customarily takes from 3 to 6 h. Depending on the amount of hydride used (from 0.8 to 1.1 g or from 1.7 to 2 g per g of perylimide) the perylene derivatives Ie and Ik are preparable respectively.
In principle it is also possible to combine the preparation of the perylene derivatives I with the synthesis of the perylene pigments by incipiently reducing the as-synthesized reaction mixture with a deficiency of hydride II. True, this will not provide the perylene derivatives I in a specific manner, but it does likewise provide transparent pigment preparations having excellent application properties.
Finally, reaction especially of perylene-3,4,9,10-tetracarboxylic dianhydride with organometallics may be used to provide in addition perylene derivatives I which contain a xe2x95x90CHR11 group instead of a carbonyl oxygen atom.
Particularly useful for this purpose are organometallics of the general formula III
(Rxe2x80x3)qM3xe2x80x83xe2x80x83III
where
M3 is HalMg, Li, Na or Li2CuCN;
Hal is chlorine, bromine or iodine;
Rxe2x80x3 is alkyl, cycloalkyl, aryl or alkoxy;
q is 1 or, when M3 is Li2CuCN, 2.
Examples of particularly useful organometallics III are organolithiums, such as methyllithium and butyllithium, and especially the Grignard compounds Rxe2x80x3MgHal, eg. CH3MgCl, with which a xe2x95x90CH2 group or a xe2x80x94C4H8 group can be introduced into the perylene derivative I.
The reaction with the organometallics III is customarily carried out in the presence of an apolar aprotic solvent, for example tetrahydrofuran.
An example of this type of reaction is the preparation of the perylene derivative In by reaction of perylene-3,4,9,10-tetra-carboxylic dianhydride with methylmagnesium chloride. A subsequent reaction with a primary amine can be used to prepare the corresponding monoimide I (eg. In).
Similarly, reaction with organometallics of the formula IIIxe2x80x2
Rxe2x80x2xe2x80x3M4xe2x80x83xe2x80x83IIIxe2x80x2
where Rxe2x80x2xe2x80x3 is aryl and M4 is lithium or sodium, can be used to introduce aryl groups into the perylene derivatives I according to the invention. A particularly useful organometallic IIIxe2x80x2 is phenyllithium.
The perylene derivatives I according to the invention are very useful as crystallization modifiers for organic pigments, especially for perylene pigments.
To this end, the perylene derivatives I may be added even in the course of the pigment synthesis. Preferably, however, the perylene derivatives I are not used until the grinding of the crude pigment. Generally, the grinding is carried out in the presence of from 0.02 to 5% by weight, preferably from 0.2 to 2% by weight, of perylene derivative I, based on the resulting pigment preparation. The grinding step may usefully take the form of dry grinding, in which case it is subsequently customary to carry out a swelling step, or of a wet grind in solvents customarily used for a swelling step, especially in an aqueous medium.
To facilitate the grinding step, it is advisable to add a resin. Preference here is given to rosins, such as rosin itself and its generally known derivatives, eg. dimerized, polymerized and hydrogenated rosin and its reaction products with maleic anhydride and fumaric anhydride. It is possible to add up to 18% by weight, preferably from 8 to 15% by weight, of resin, based on the resulting pigment preparation.
It will be appreciated that further customary pigment preparation additives, such as surfactants, may be used. Suitable quantities for these additives generally range from 0 to 5% by weight.
Dry grinding can be carried out in a ball mill, in a planetary mill or in a jet mill. Wet grinding is particularly usefully carried out in a ball mill, which may be stirred, in which case it is preferably operated at from 100 to 2000 rpm. Useful grinding media include for example silicon/aluminum/zirconium oxide (SAZ) beads, glass beads, agate balls or sand grains, which may have diameters in the region of about 1 cm or in the range from 0.3 to 30 mm.
Grinding is customarily carried on until a median pigment particle size typically of about 30-100 nm is obtained. Dry grinding accordingly typically takes from 2 to 20 h, especially from 8 to 12 h.
The solvent treatment which follows the dry grinding step can be carried out in various ways.
In one variant, the millbase (after removal of the grinding media) is swollen in a preferably concentrated mineral acid, for example in 50-100% by weight hydrochloric acid, in 50-100% by weight sulfuric acid or mixtures thereof at from 0 to 70xc2x0 C. for from 2 to 20 h and then precipitated in ice-water. Preference is given to swelling in concentrated sulfuric acid (generally 75-79% by weight of sulfuric acid) at room temperature.
Another variant is the similarly conducted swelling in aqueous solutions of inorganic bases, such as sodium hydroxide, potassium hydroxide, calcium carbonate and sodium bicarbonate, or organic bases, such as methylamine. The pigment obtained is here separated from the aqueous phase by filtration.
Finally, the millbase can also be swollen in water, organic solvents or aqueous-organic mixtures. Useful organic solvents in this context are in particular water-miscible solvents, such as dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran and especially alkylene glycol monoalkyl ethers, in particular ethylene glycol monobutyl ether. The treatment temperatures here are generally in the range from 5 to 100xc2x0 C. and the treatment times typically range from 2 to 16 h.
The similarly inventive pigment preparations include as essential pigments
A) at least one organic pigment from the class of the perylene pigments and
B) at least one perylene derivative of the formula I.
The pigment preparations preferably further include C) at least one rosin.
It will be appreciated that further customary pigment preparation additives D), for example surfactants, may be included.
The pigment preparations of the invention have the following composition in particular:
A) from 80 to 99.98% by weight, preferably from 85 to 89% by weight, of the perylene pigment,
B) from 0.02 to 5% by weight, preferably from 0.2 to 2% by weight, of the perylene derivative I,
C) from 0 to 18% by weight, preferably from 8 to 15% by weight, of the rosin, and
D) from 0 to 5% by weight of customary additives.
Any known perylene pigments may be used. As well as perylene-3,4,9,10-tetracarboxylic dianhydride (C.I. Pigment Red 224) these include for example the unsubstituted perylene-3,4,9,10-tetracarboxylic diimide (C.I. Pigment Violet 29) and the N,Nxe2x80x2-di(C1-18-alkyl)-, N,Nxe2x80x2-di(C5-7-cycloalkyl)- and N,Nxe2x80x2-diaryl-substituted diimides (aryl: especially phenyl and C1-4-alkyl- or -alkoxy- or phenylazo-substituted phenyl) (eg.: C.I. Pigment Red 123, 149, 178, 179 and 190).
The pigment preparations of the invention are notable for their excellent application properties, especially their color properties, in particular their color strength and transparency, and their Theological properties. The pigment particles are substantially isometric with a particle size distribution typically from 50 to 100 nm.
They are very useful for coloring aqueous and nonaqueous systems. Examples of useful application media are plastics, coatings, paints, printing inks and toners.